HARD SURFACE CLEANING COMPOSITIONS COMPRISING POLYMERS

Abstract: Use of certain, relatively long chain, anionic water-soluble polymers in acidic or neutral surfactant compositions brings a primary cleaning benefit in addition to a secondary (anti-soiling) benefit. Commonplace acrylic, methacrylic and maleic anhydride derived polymers exhibit this effect in acidic solutions of nonionic surfactants to the same extent as expensive, quaternised cationic polymers. The invention provides liquid cleaninig composition of pH 2-8, comprising: a) 1-30 %wt nonionic surfactant; b) 0.005-5 %wt of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, said polymer being free of quaternary nitrogen groups.

Description: HARD SURFACE CLEANING COMPOSITIONS COMPRISING POLYMERS Technical Field The present invention relates to general purpose, particularly, hard surface, liquid cleaning compositions comprising surfactants and polymeric components. Background of the Invention In traditional cleaning of hard surfaces such as wood, glazed tiles, painted metal and the like, it is known to follow soil removal using surfactant or solvent based compositions with the application of a lacquer, wax or polish as a separate operation so as to seal the surface and reduce the rate of soil redeposition. This two-step cleaning and sealing operation is time-consuming and complex. It is known to incorporate components into a surfactant- based composition with the intention that deposition of such components onto surfaces will provide a protective layer in a one step cleaning operation. US 3679592 (1972) discloses alkaline, cleaning and soil preventative compositions which comprise surfactant and l-10%wt, particularly 4%, of a film forming component of specified structure having a molecular weight in the range 500 to 100,000. In use, the compositions are said to inhibit stain deposition and assist soil removal. GB 1528592 (1978) discloses alkaline, floor cleaning compositions which comprise an organic, polycarboxylic acid co-polymer having a molecular weight in the range 100,000-2,500,000 which is soluble in aqueous solutions having a pH of 8.5 or above. These polymers are readily available in commercial quantities. GB 1534722 (1978) discloses granular hard surface cleaning compositions which comprise surfactant and, as "a soil removal improvement mixture", a polyvinyl alcohol or pyrrolidone and a biopolysaccharide. These polymers have molecular weights ranging from around 5000 to around 360,000 and are available in industrially useful quantities. The compositions form alkaline solutions. US 4252665 (1979) discloses aqueous, alkaline, hard surface cleaning compositions of pH 9-12 which comprise a 'detergency-boosting' acrylic copolymer having a molecular weight substantially in excess of 100,000 in combination with anionic surfactants. US 07/297807, as described in EP 0467472 A2 (Colgate Palmolive) demonstrates that the incorporation of 2.3% of a 15-20% aqueous solution of the cationic polymer poly- [beta(methyl diethyl-ammonium) ethyl-methacrylate] in a mixed nonionic surfactant system for hard surface cleaning results in significant improvement of ease of subsequent re-cleaning of previously soiled and cleaned ceramic tiles. These cationic polymers are rather more expensive than commonplace acrylic and methacrylic polymers and some doubt has been cast upon the environmental acceptability of cationic species containing quaternary nitrogen. It is known for surfactant-based cleaning compositions to contain structuring agents to aid in providing appropriate rheological properties to enhance their distribution and adherence of the composition to the hard surface to be cleaned, particularly to provide enhanced cling on sloping surfaces. Known structuring agents include polymers such as poly- saccharides, e.g. sodium carboxymethyl cellulose and other chemically modified cellulose materials, xanthan gum and other non-flocculating structuring agents such as Biopoly er PS87 referred to in US Patent No. 4 329 448. Polymers of acrylic acid cross-linked with a poly functional agent, for example CARBOPOL R , are also used as structuring agents. The amount of such structuring agents can be as little as 0.001% but is more typically at least 0.01% by weight of the composition. A further function of such structuring agents is to suspend particulate components, such as abrasives. It is also known to employ at least partially esterified resins such as an at least partially esterified adduct of rosin and an unsaturated dicarboxylic acid or anhydride, or an at least partially esterified derivatives of co- polymerisation products of ono-unsaturated aliphatic, cycloaliphatic or aromatic monomers having no carboxy groups and unsaturated dicarboxylic acids or anhydrides thereof as additives. The purpose of such materials is to modify the wetting properties of the composition so as to produce a 'streak-free' finish after drying. Typical examples of suitable copolymers of the latter type are copolymers of ethylene, styrene and vinyl- ethylether with maleic acid, fumaric acid, itaconic acid, citraconic acid and the like and the anhydrides thereof including the styrene/maleic anhydride copolymers. EP 0467472 A2 discloses that soil release promoting polymers such as, but not limited to, the cationic poly- [beta(methyl diethyl-ammonium) ethyl-methacrylate] are also effective in combination with anionic and cationic surfactant . In that published application it is stated that 'said adsorbed polymer forms a residual anti-soiling hydrophilic layer of said soil release promoting polymer on said surface, whereby removal of soils subsequently deposited thereupon requires less work than in the absence of said residual layer' . The molecular weight range of the polymers falls into the range 4,000-100,000 although the use of polymers having a molecular weight above 50,000 is discouraged for solubility reasons (see EP 467472, page 3 paragraph 3) . EP 0379256 discloses similar compositions to the above- mentioned document, having up to 2%wt of an optional quatemised, anti-static, polymer of molecular weight in the range of 2,000 - 500,000, and being characterised by an acidic pH of 2-4 and a 2-4%wt of a nonionic surfactant system. Specific examples relate to compositions having a pH of 2.5 and comprising 2.2%wt of a mixed nonionic system and 0.07% of the specified cationic polymer. The modified polymer is again said to function as a soil release agent. In addition to the above it is known from US 4606842 to use low molecular weight polyacrylic resins as a builder in glass cleaning compositions of the spray-on, wipe-off type. Baker et al in US 4690779 discloses the use of the combination of polymers of polyacrylic acid having a molecular weight below 5000 with certain nonionic surfactants in hard surface cleaning compositions. The primary function of the polymer in these systems is as a builder. From the above it can be seen that it is known to include certain polymers in generally alkaline hard surface cleaning compositions so as to obtain either a primary cleaning benefit when the composition is first used on the surface or a secondary cleaning benefit by modification of the surface so as hinder soil deposition or otherwise facilitate repeated cleaning. As will be illustrated by way of example hereafter, known compositions are generally not efficient in both primary and secondary cleaning. Brief Description of the Invention We have now determined that the use of certain, relatively long chain, anionic water-soluble polymers in acidic or neutral surfactant based composition brings a surprising initial cleaning benefit in addition to the anti-soiling benefit. Surprisingly, we have found that commonplace acrylic, methacrylic and maleic anhydride derived polymers exhibit this effect in acidic solutions of nonionic surfactants to the same extent as expensive cationic polymers. Accordingly the invention provides liquid cleaning composition of pH 2-8, comprising: a) l-30%wt nonionic surfactant, b) 0.005-5%wt of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, said polymer being free of quaternary nitrogen groups. Detailed Description of the Invention Without wishing to be limited by any theory of operation, it is believed that the cleaning benefit of the water- soluble polymer arises from a phase separation of the nonionic surfactant causing penetration into and/or deposition onto soil, resulting in a higher effective surfactant concentration, than is found in compositions which are free of polymer. An alternative explanation is that deposition of surfactant at the soil surface may be enhanced by the formation and deposition of a polymer surfactant complex. Polymers The water soluble polymer of the above-mentioned size range is an essential component of the compositions according to the present invention. Surprisingly, the preferred polymers in embodiments of the present invention are those which are readily available in the marketplace. These are polymers of acrylic or methacrylic acid or maleic anhydride, or a co-polymer of one or more of the same either together or with other monomers. Particularly suitable polymers include polyacrylic acid, polymaleic anhydride and copolymers of either of the aforementioned with ethylene, styrene and methyl vinyl ether. The most preferred polymers are maleic anhydride co¬ polymers, preferably those formed with styrene, acrylic acid, methyl vinyl ether and ethylene. Preferably, the molecular weight of the polymer is at least, 5000, more preferably at least 50,000 and most preferably in excess of 100,000. Typically, the surfactant based cleaning compositions comprise at least 0.01wt% polymer, on product. Unexpectedly, it has been found that the positive benefit of the presence of polymer can be identified even when very low levels of polymer and surfactant are present. This property of a low concentration threshold is particularly advantageous in applications of the invention where considerable dilution is expected. Preferably the level of polymer is 0.05-5.0wt% at which level the anti-resoiling benefits become particularly significant. More preferably 0.2-2.0wt% of polymer is present. We have determined that higher levels of polymer do not give significant further advantage with common dilution factors, while increasing the cost of compositions. It is believed that high levels of polymer increase the viscosity of the product and hinder product wetting and penetration of the soil. However, for concentrated products which are diluted prior to use, the initial polymer level can be as high as 5%wt. In the context of the present invention, anionic polymers are those which carry a negative charge or similar polymers in protonated form. Mixtures of polymers can be employed. As mentioned above, the molecular weight of the polymer is below 1 000 000 Dalton. As the molecular weight increases the cleaning benefit of the polymer was reduced. Surfactants It is essential that compositions according to the present invention comprise at least one nonionic surfactant. The composition according to the invention comprise detergent actives which can be chosen from nonionic detergent actives. We have determined that an detrimental effect occurs if the anionic polymers are used together with anionic surfactant only or with mixtures of anionic and nonionic surfactant which largely comprise anionic surfactant. Suitable nonionic detergent active compounds can be broadly described as compounds produced by the condensation of alkylene oxide groups, which are hydrophilic in nature, with an organic hydrophobic compound which may be aliphatic or alkyl aromatic in nature. The length of the hydrophilic or polyoxyalkylene radical which is condensed with any particular hydrophobic group can be readily adjusted to yield a water-soluble compound having the desired degree of balance between hydrophilic and hydrophobic elements. Particular examples include the condensation product of aliphatic alcohols having from 8 to 22 carbon atoms in either straight or branched chain configuration with ethylene oxide, such as a coconut oil ethylene oxide condensate having from 2 to 15 moles of ethylene oxide per mole of coconut alcohol; condensates of alkylphenols whose alkyl group contains from 6 to 12 carbon atoms with 5 to 25 moles of ethylene oxide per mole of alkylphenol; condensates of the reaction product of ethylenediamine and propylene oxide with ethylene oxide, the condensates containing from 40 to 80% of polyoxyethylene radicals by weight and having a molecular weight of from 5,000 to 11,000; tertiary amine oxides of structure R 3 N0, where one group R is an alkyl group of 8 to 18 carbon atoms and the others are each methyl, ethyl or hydroxy-ethyl groups, for instance dimethyldodecylamine oxide; tertiary phosphine oxides of structure R 3 P0, where one group R is an alkyl group of from 10 to 18 carbon atoms, and the others are each alkyl or hydroxyalkyl groups of 1 to 3 carbon atoms, for instance dimethyldodecylphosphine oxide; and dialkyl sulphoxides of structure R 2 S0 where the group R is an alkyl group of from 10 to 18 carbon atoms and the other is methyl or ethyl, for instance methyltetradecyl sulphoxide; fatty acid alkylolamides; alkylene oxide condensates of fatty acid alkylolamides and alkyl mercaptans. The amount of nonionic detergent active to be employed in the composition of the invention will generally be from 1 to 30%wt, preferably from 10 to 20%wt, and most preferably from 12 to 20%wt. Levels of around 15% active are particularly preferred as little increase in neat-use cleaning performance is found at higher levels, although such higher levels can be employed in products intended to be considerably diluted prior to use. Optionally, anionic surfactant can be present in relatively small proportions. Suitable anionic detergent active compounds are water- soluble salts of organic sulphuric reaction products having in the molecular structure an alkyl radical containing from 8 to 22 carbon atoms, and a radical chosen from sulphonic acid or sulphur acid ester radicals and mixtures thereof. Examples of anionic detergents are sodium and potassium alcohol sulphates, especially those obtained by sulphating the higher alcohols produced by reducing the glycerides of tallow or coconut oil; sodium and potassium alkyl benzene sulphonates such as those in which the alkyl group contains from 9 to 15 carbon atoms; sodium and potassium secondary alkanesulphonates; sodium alkyl glyceryl ether sulphates, especially those ethers of the higher alcohols derived from tallow and coconut oil; sodium coconut oil fatty acid onoglyceride sulphates; sodium and potassium salts of sulphuric acid esters of the reaction product of one mole of a higher fatty alcohol and from 1 to 6 moles of ethylene oxide; sodium and potassium salts of alkyl phenol ethylene oxide ether sulphate with from 1 to 8 units of ethylene oxide molecule and in which the alkyl radicals contain from 4 to 14 carbon atoms; the reaction product of fatty acids esterified with isethionic acid and neutralised with sodium hydroxide where, for example, the fatty acids are derived from coconut oil and mixtures thereof. The preferred water-soluble synthetic anionic detergent active compounds are the ammonium and substituted ammonium (such as mono, di and triethanolamine) , alkali metal (such as sodium and potassium) and alkaline earth metal (such as calcium and magnesium) salts of higher alkyl benzene sulphonates and mixtures with olefinsulphonates and higher alkyl sulphates, and the higher fatty acid monoglyceride sulphates. The most preferred anionic detergent active compounds are higher alkyl aromatic sulphonates such as higher alkyl benzene sulphonates containing from 6 to 20 carbon atoms in the alkyl group in a straight or branched chain, particular examples of which are sodium salts of higher alkyl benzene sulphonates or of higher-alkyl toluene, xylene or phenol sulphonates, alkyl naphthalene sulphonates, ammonium dia yl naphthalene sulphonate, and sodium dinonyl naphthalene sulphonate. The amount of synthetic anionic detergent active to be employed in the detergent composition of this invention will generally be from 0.5 to 50%wt (on total active), preferably less than 33%wt (on total active) . For products containing around 15%wt of surfactant, the level of anionic surfactant should preferably not exceed 5%wt on product. It is also possible optionally to include amphoteric, cationic or zwitterionic detergent actives in the compositions according to the invention. Suitable amphoteric detergent-active compounds that optionally can be employed are derivatives of aliphatic secondary and tertiary amines containing an alkyl group of 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water-solubilising group, for instance sodium 3-dodecylamino-propionate, sodium 3- dodecylaminopropane sulphonate and sodium N-2-hydroxydodecyl-N-methyltaurate. Suitable cationic detergent-active compounds are quaternary ammonium salts having an aliphatic radical of from 8 to 18 carbon atoms, for instance cetyltrimethyl ammonium bromide. Suitable zwitterionic detergent-active compounds that optionally can be employed are derivatives of aliphatic quaternary ammonium, sulphonium and phosphonium compounds having an aliphatic radical of from 8 to 18 carbon atoms and an aliphatic radical substituted by an anionic water- solubilising group, for instance 3-(N,N-dimethyl-N-hexadecylammonium)propane-l-sulphonate betaine, 3-(dodecyImethy1 sulphonium) propane-1-sulphonate betaine and 3-(cetyImethylphosphonium) ethane sulphonate betaine. Further examples of suitable detergent-active compounds are compounds commonly used as surface-active agents given in the well-known textbooks "Surface Active Agents", Volume I by Schwartz and Perry and "Surface Active Agents and Detergents", Volume II by Schwartz, Perry and Berch. The total amount of detergent active compound to be employed in the detergent composition of the invention will generally be from 1.5 to 30%, preferably from 2 to 20% by weight, most preferably from 10-20wt%. Minors The composition according to the invention can contain other ingredients which aid in their cleaning performance. For example, the composition can contain detergent builders other than the special water-soluble salts, as defined herein, such as nitrilotriacetates, polycarboxylates, citrates, dicarboxylic acids, water- soluble phosphates especially polyphosphates, mixtures of ortho-and pyrophosphate, zeolites and mixtures thereof. Such builders can additionally function as abrasives if present in an amount in excess of their solubility in water as explained herein. In general, the builder, other than the special water-soluble salts when employed, preferably will form from 0.1 to 25% by weight of the composition. Metal ion sequestrants such as ethylenediaminetetraacetates, amino-polyphosphonates (DEQUEST R ) and phosphates and a wide variety of other poly- functional organic acids and salts, can also optionally be employed. A further optional ingredient for compositions according to the invention is a suds regulating material, which can be employed in compositions according to the invention which have a tendency to produce excessive suds in use. One example of a suds regulating material is soap. Soaps are salts of fatty acids and include alkali metal soaps such as the sodium, potassium, ammonium and alkanol ammonium salts of higher fatty acids containing from about 8 to about 24 carbon atoms, and preferably from about 10 to about 20 carbon atoms. Particularly useful are the sodium and potassium and mono-, di- and triethanolamine salts of the mixtures of fatty acids derived from coconut oil and ground nut oil. When employed, the amount of soap can form at least 0.005%, preferably 0.5% to 2% by weight of the composition. A further example of a suds regulating material is an organic solvent, hydrophobic silica and a silicone oil or hydrocarbons. Compositions according to the invention can also contain, in addition to the ingredients already mentioned, various other optional ingredients such as pH regulants, colourants, optical brighteners, soil suspending agents, detersive enzymes, compatible bleaching agents, gel- control agents, freeze-thaw stabilisers, bactericides, preservatives, solvents, fungicides, insect repellents, detergent hydrotropes perfumes and opacifiers. It is preferable that the compositions of the present invention are essentially free of abrasive particles. Experiments have shown that the presence of abrasive reduces the cleaning benefit due to the polymer although abrasive would in itself provide a separate cleaning benefit. It is believed that the abrasive, surfactant and polymer form a complex which reduces the effective concentration of the surfactant at the surface being cleaned. As mentioned above, the pH of the compositions according to the present invention is acidic or neutral. We have determined that improved cleaning and/or anti-resoiling benefit is obtained at these pH's. The preferred pH of the products is 3-7 with a pH in the range 3-6 being more preferred and a pH of 4-6 being particularly preferred so as to provide a balance between the hazards of acid compositions and the advantages of acids for removing limescale. Particularly preferred compositions according to the present invention are mobile aqueous liquids, having a pH of 3-6 which comprise: a) 10-20%wt of a alkoxylated alcohol, nonionic surfactant, less than 3%wt of anionic surfactants, c) 0.2-2%wt of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, said polymer being a polymer of at least one of acrylic acid, methacrylic acid or maleic anhydride, with at least one of acrylic acid, methacrylic acid, maleic anhydride, ethylene, styrene and methyl vinyl ether, and said polymer being essentially free of quaternary nitrogen groups. In order that the present invention may be further understood it will be described hereafter by way of example and with reference to the accompanying figures wherein: Figure 1: is a graph showing the effect of polymer concentration on cleaning effort and anti-resoiling benefit, and, Figure 2: is a graph showing the relation of primary and secondary cleaning benefits for a range of polymer types. EXAMPLES Examples 1-8 use materials as mentioned below: Sokolan series (TM) ex. BASF Gantrez series (TM) ex. GAF Scripset 520 (TM) ex Monsanto EMA 31 ex Monsanto SCMC (Courlose A600) ex Courtaulds 6047 polyacryamides ex. Allied Colloids FRS 3966 ex Allied Colloids Jaguar C162 ex Meyhall Polyethylene Oxide (WSRN 80) ex Union Carbide Polyvinyl Pyrollidone ex PolySciences The polyvinyl pyrollidone had a molecular weight of circa, 386000 Dalton. EXAMPLE la-c Comparison with cationic polymers 0.25mg/cm 2 (based on non-volatiles) of soil were deposited on an 'A4' sized area of 'DECAMEL' (RTM ex Formica) test surface by spraying. The soil comprised 1% glycerol tripalmitate, 0.5% glycerol trioleate, 0.5% kaolin, 0.2% liquid paraffin, 0.1% palmitic acid, 0.02% carbon black in methylated spirits. The soil was allowed to age for 24 hours at room temperature prior to cleaning. The effort used to remove the soil from the test surface using a cellulosic spongecloth was measured. Formulations comprised nonionic surfactant and water with and without polymer. The surfactant employed was Imbentin 91-35 OFA (TM) (C9-C11 alkyl, 3-5 EO alkyl ethoxylate ex. KOLB) . The polymers illustrative of the present invention were a polyacrylic acid (ex BDH) which had an average molecular weight of 230,000 Daltons. The cationic polymer used in the comparative examples was Polymer JR-400 (TM: ex. Union Carbide) and had an average molecular weight of 400,000 Daltons. The formulations are given in Table 1 below, together the effort required in the cleaning operation. Results given are geometric means of eight replicate experiments. In order to remove day to day variability, arising from differences in soil level data is normalised such that the effort required to clean a DECAMEL tile with the same polymer-free composition is constant. From the results given under 'initial' it can be seen that the compositions according to the present invention show an improved cleaning performance over the comparative example la, where no polymer was present. This improvement is statistically significant at the 95% confidence level. In order to investigate the re-soiling performance, the DECAMEL sheets were re-soiled and cleaned again using the same soil and the same cleaning protocol. Cleaning results for the first and second re-cleaning cycles are given under 'same(2)' and 'same(3)'. These results show the significant benefit of the presence of the polymer. For compositions which did not contain polymer (see example la) the effort required in the subsequent cleaning cycles remains essentially constant. It can be seen that significantly less effort is required where surfaces are cleaned using a polymer containing composition and are subsequently recleaned using the same composition. Results given under 'normal(4)' are results obtained by subsequently cleaning the test surfaces used in examples la-e with the composition used in example la (i.e. surfactant alone) . This indicates that the benefit of the present invention persisted when the test surfaces were cleaned with a conventional surfactant-only composition. It will be noted that the initial cleaning benefits of the polymers according to the invention (examples lc and le) are comparable, if not directionally slightly better than those attained with the quatemised polymer (as used in comparative examples lb and Id) . TABLE 1 la lb lc Id le Imbentin 10% 10% 10% 10% 10% Polymer JR - .25% - 1% Polyacrylic Acid - - .25% - 1% (mol wt 230kD) Water to 100% Ph 4.2 4.4 3.7 4.6 3.3 Initial 1 .29 .24 .36 .25 Same(2) 1 .11 .15 .12 .14 Same(3) 1 .05 .06 .06 .06 Normal 1 .18 .18 .17 .21 EXAMPLE 2d-σ Effect of polymer levels Example 1 was repeated using the formulations given in Table 2 below: except that the polyacrylacid used was VERSICOL Ell (RTM) (ex. Allied Colloids: mol wt 250kD) . Effort to clean the DECAMEL (RTM) tiles is expressed in terms of the logarithm (base 10) of the effort required. Examples were repeated both with and without polymer and at differing concentrations of surfactant. The values given are the means of four replicates. 'Initial' results were obtained using the compositions specified with polymer. 'Normal (1)' results were obtained by cleaning using the compositions as specified but without polymer. 'Same(2)' values were obtained by re-cleaning the tiles originally cleaned with the polymer-containing composition, to obtain the results given at 'Initial(1)' using the same composition in the same manner as the tiles had initially been cleaned. 'Normal(2)' values were obtained by cleaning the re-soiled tiles from 'Normal(1)' with a polymer free composition having the same surfactant level. Normal(3-5) values were obtained by cleaning the tiles originally cleaned by a polymer-containing composition (to obtain the 'Same(2) # results) with a polymer-free composition. In all the recleanings in the Normal(3-5) series the same level of surfactant (7%wt: IMBENTIN) was used. TABLE 2 2d 2e 2£ 2g Imbentin 16% 8% 4% 2% Polyacrylic Acid 1% 0.5% 0.25% 0.15% (mol wt 250kD) Water to 100% Log initial effort Required Initial(1) 2.36 2.38 2.69 3.35 Normal (1) 2.37 3.04 3.43 ** ★ * Same(2) 2.18 2.14 2.18 2.80 Normal(2) no significant reduction from Normal(1) Recleaning of 'Same(2) ' without polymer Normal (3) 2.17 1.98 1.99 2.02 Normal(4) 2.86 2.92 2.90 2.83 Normal (5) 3.02 3.04 2.99 3.03 j From the results it can be seen that the presence of polymer has a primary cleaning benefit,: i.e. less cleaning effort is required in the presence of polymer than in its absence (compare the 'Normal (1)' results with the 'Initial(1) ' results. The magnitude of this effect increases markedly at lower surfactant concentrations. This is believed to be due to the excellent primary cleaning expected at high surfactant levels masking the effect of the polymer. In example 2g it proved impossible to clean the tile using reasonable efforts using a low level of surfactant in the absence of polymer. It can also be seen that the effect of polymer persists in subsequent cleaning cycles but the effect is reduced as the number of cycles is increased. Significantly, low levels of polymer and surfactant show slight improvement in secondary cleaning performance over higher levels. Thus, compositions comprising the low levels of surfactant and polymer clean at least as well as the compositions containing higher levels of these components: compare 2d with 2f in which four times the levels of surfactant and polymer are present yet the same effort was required to clean the tile. Compositions which contain no polymer do not clean when only low levels of surfactant are present. It was also determined that compositions which contain no polymer show no reduction in effort required on repeated use. EXAMPLES 2h-l Comparison with commercial hard surface cleaners Examples 2h-21 compare the effort required using very dilute solutions of the products listed in Table 2c. The compositions are diluted to typical floor-cleaning dilutions as recommended by the manufacturers (approximately 3g/l) . The formulation of the embodiment of the invention is: 28% IMBENTIN, 2% polyacrylic acid (250kD: VERSICOL Ell (RTM), ex Allied Colloids) . The formulation of the comparative example using nonionic alone omitted the polymer. Results for percentage soil removal on a hydrophobic surface, determined by a standard colourimetric method, after 40 cleaning strokes, were obtained using an in-line linear scrubber of the SHEEN (RTM) type using an applied pressure of 80g/cm2. The surface was DECAMEL (RTM) and pre-soiled with 0.061mg/cm2 (based on non-volatiles) of soil. Cleaning was performed with a cellulosic sponge pre-impregnated with the appropriate cleaning solution. Results for percentage soil removal on a hydrophilic surface were determined using the same soil applied to ceramic floor tiles, under identical conditions but with a single cleaning stroke. Both sets of experiments were performed in three series with soil types of: a) 1% glycerol tripalmitate, 0.5% glycerol trioleate, 0.5% kaolin, 0.2% liquid paraffin, 0.1% palmitic acid, 0.02% carbon black in methylated spirits, (i.e. 80:20 fat :particulate) b) as (a) with 50:50 fat particulate, and, c) as (a) with 20:80 fat particulate. The use of these three different model soil types and two surfaces illustrates the performance of the compositions in practice. Three replicates were performed with each of the three soil type and the mean values over all nine measurements, as expressed in the table, are taken as indicative of the performance, in practice, of the compositions on the surface indicated. TABLE 3 Ex. Solution DECAMEL ceramic 2h Embodiment 65% 47% 2i Nonionic alone 58% 35% 2j AJAX COMPACT (RTM) 45% 30% 2k FLASH ULTRA (RTM) 40% 12% 21 FLASH LIQUID (RTM) 28% 8% From these results it can be seen that the embodiment of the invention significantly outperforms the comparative examples under the above-mentioned conditions. In further experiments it was determined that the embodiment used in example 2h gave less residues and enhanced shine (as determined by gloss readings) than the comparative formulations of examples 2i-21 on black ceramic tiles. EXAMPLE 3 Anionic Surfactant/Anionic Polymer (Comparative example) Example 1 was repeated using simplified formulations consisting of anionic surfactant only in water with and without anionic or cationic polymer. The surfactant employed was a magnesium salt of PAS. The anionic polymer was polyacrylic acid as used in example 1. The cationic polymer was Polymer JR as used in example 1. The formulations are given in Table 4 below, together the effort required in the cleaning operation as mentioned in example 1. Figures given are geometric means of eight replicate experiments, normalised to represent the data as if compositions free of polymer always require the same cleaning effort. Initial cleaning performance data is presented at 'Initial(1) ' . It can be seen that the polymer containing compositions (3b-3e) have no significant primary cleaning benefits, but rather that it is generally more difficult to clean a surface with the anionic surfactant compositions containing anionic or cationic polymer than similar compositions without the polymer: e.g. in example 3c it can be seen that for polymer containing compositions around two-and-a-half times the effort was required for initial cleaning as compared with polymer free compositions. In order to investigate the re-soiling performance, the DECAMEL sheets were re-soiled and cleaned again using the same protocol. Cleaning results for the first and second re-cleaning cycles are given under 'Same(2)' and 'Same(3)'. These results show a generally negative benefit believed to be due to the presence of an anionic polymer and a surfactant system of the same charge type. Results given under 'Normal(4)' are results obtained by subsequently cleaning the test surfaces used in examples 3a-e with the composition used in example 3a, i.e. cleaning with surfactant only (an essentially conventional composition) in the absence of polymer. This indicates that the negative benefit of anionic polymers persisted when the test surfaces were cleaned with a conventional surfactant-only composition ^ These results also show that cationic polymers exhibit a secondary cleaning benefit which is not seen with anionic polymers in the presence of anionic surfactant. TABLE 4 3a 3b 3c 3d 3e Magnesium-PAS 5% 5% 5% 5% 5% Polymer JR - 0.25% - 1% - Polyacrylic acid - - 0.25% - 1% Water to 100% Ph 6.5 5.5 3.4 5.3 3.0 Initial(1) 1 1.18 2.42 1 1.18 Same(2) 1 0.20 2.10 0.18 1.10 Same(3) 1 0.15 2.01 0.16 0.90 Normal(4) 1 0.22 1.47 0.22 1.26 Similar experiments were performed with the cationic polymer (Polymer JR) and cationic surfactant (Tetradecyl trimethyl ammonium hydrogen sulphate) . No benefits were discerned. It is believed that this lack of benefit was due to the surfactant and the polymer having the same charge and the consequent inability of the surfactant and the polymer to form a complex. EXAMPLE 4 Comparison with other polymers A further series of experiments were performed using the materials mentioned in table 5 below. Simplified formulations consisting of nonionic surfactant (10wt%) and water with and without polymer. The surfactant employed was Imbentin 91-35 OFA (C9-C11 alkyl, 3-5 EO alkyl ethoxylate) . The polymers are as listed in the table and were present at a level of 0.5wt%. Results were normalised such that the initial cleaning effort required with the surfactant alone was 100%. The recleaning benefit was assessed by cleaning the surfaces with a 7.5wt% aqueous solution of nonionic surfactant alone and measuring the effort required: results again being normalised assuming 100% cleaning effort for surfactant alone. TABLE 5 Initial Re-cleaning Maleic Anhydride Copolymers Acrylic acid 4a Sokolan CP12 (TM) 24 10 4b Sokolan CP13 (TM) 32 17 Methyl vinyl ether 4c Gantrez AN119 (TM) 25 8 4d Gantrez AN169 (TM) 34 12 Styrene 4e Scripset 520 (TM) 29 9 Ethylene 4f EMA 31 22 11 Carboxylate Polymer 4g SCMC 48 22 Cationic Polymers Polyacrylamides 4h 6047A 34 21 4i 6047B 42 26 4j 6047C 47 23 4k 6047D 82 16 41 FRS 3966 80 24 Modified Guar Jaguar C162 54 22 Nonionic Polymers 4n Polyethylene Oxide 29 49 4o Polyvinyl Pyrollidone 37 43 These results are presented in graphical form in figure 2 In that figure, primary (initial) and secondary (re- cleaning) performance are plotted on separate axes. Reference to the data in figure 2 is by means of the co¬ ordinates. Examples of nonionic polymers, as mentioned in GB 1534722 such as the coating agents PO (at 49,29) and PVP (at 43,37), show particularly poor recleaning benefits although the primary cleaning performance is good. The cationic polymers show some benefits both in primary and secondary cleaning, although the trend indicates that the two factors have an inverse relationship, that is, better cleaning in one situation is generally associated with worse performance in the other: compare polyacrylamide at (82,16) and polyacryla ide at (42,26). It is clear from figure 2 that more significant benefits are obtained with the anionic polymers of the present invention, and in particular with the maleic anhydride co- polymers, preferably those formed with styrene, acrylic acid, methyl vinyl ether and ethylene. The results show that with the exception of carboxy methyl cellulose (22,48) and the Sokolan CP13 (TM) (17,32) the anionic polymers showed generally improved performance over all the comparative examples as regards both primary and secondary cleaning. EXAMPLE 5 Effect of Polymer Concentration Turning to figure 1 there is shown a graph of the effect of polymer concentration (230kD, ex BDH) on cleaning effort and anti-resoiling benefit. All compositions were at the natural pH of 4, and comprised surfactant (Imbentin 91-35 OFA: C9-C11 alkyl, 3-5 EO alkyl ethoxylate) at a level of 10%wt. The cleaning and anti-resoiling benefits were assessed as in Example 4. The figure illustrates that with the compositions of the present invention the initial (primary) cleaning benefit becomes significant even at very low levels of polymer and persists as the level of polymer increases. The anti- resoiling benefits become apparent at levels of around 0.2% polymer and again persist. This is in agreement with the results obtained in example 2d-g. EXAMPLE 6 Effect of PH Table 6 shows the effect of pH for compositions of the present invention comprising 0.5% of a polyacrylic acid polymer (230kD, ex BDH) and comparative compositions which do not contain polymer. All compositions comprised surfactant (Imbentin 91-35 OFA: C9-C11 alkyl, 3-5 EO alkyl ethoxylate) at a level of 10%wt. pH was modified by the presence of NaOH. The cleaning and anti-resoiling benefits were assessed as in Example 4. Cleaning effort is expressed as the logarithm (base 10) of the effort required. TABLE 6 Primary Effort Secondary Effort PH with without with without polymer polymer polymer polymer 6a 3.5 2.25 2.45 2.25 2.72 6b 5.0 2.30 2.45 2.30 2.72 6c 7.0 2.50 2.45 2.85 2.72 6d 9.0 2.70 2.45 2.72 2.72 It can be seen that at low pH's, particularly below pH 7.0 there is a marked reduction in both the primary and secondary cleaning effort requirements of polymer containing systems over compositions comprising nonionic only.

Claims: CLAIMS 1. Liquid cleaning composition of pH 2-8, comprising: a) l-30%wt nonionic surfactant, b) 0.005-5%wt of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, said polymer being free of quaternary nitrogen groups. 2. Composition according to claim 1 comprising 0.2- 2.0%wt anionic polymer. 3. Composition according to claim 1 wherein the anionic polymer is selected from the group comprising, polymers of acrylic or methacrylic acid or maleic anhydride, a co-polymer of one or more of the same either together or with other monomers, and mixtures thereof. 4. Composition according to claim 3 wherein the polymer is selected from the group comprising polyacrylic acid, polymaleic anhydride and copolymers of either of the aforementioned with ethylene, styrene and methyl vinyl ether. 5. Composition according to claim 1 wherein the molecular weight of the polymer is in excess of 100,000. 6. Composition according to claim 1 comprising not more than 33%wt anionic detergent on total detergent actives. 7. Liquid cleaning composition of pH 3-6 comprising: a) 10-20%wt of a alkoxylated alcohol, nonionic surfactant, b) less than 3%wt of anionic surfactants, c) 0.2-2%wt of a water soluble, anionic polymer having an average molecular weight less than 1,000,000, said polymer being a polymer of at least one of acrylic acid, methacrylic acid or maleic anhydride, with at least one of acrylic acid, methacrylic acid, maleic anhydride, ethylene, styrene and methyl vinyl ether, and said polymer being essentially free of quaternary nitrogen groups.

Inventors: SHARPLES MARTIN, SHARPLES, MARTIN
Applicants: SHARPLES MARTIN, UNILEVER NV, UNILEVER PLC, SHARPLES, MARTIN, UNILEVER N.V.
Application year: 1994
Main classification: C11D1
IPC codes: C11D1, C11D3